Overkill (15) - Control creatures with a total power of 75 or more (Duel the Dragon).
Dragon Slayer (20) - Defeat Nicol Bolas in the single player campaign (Duel the Dragon).
Puzzling Grandmaster (15) - Earn Puzzling Master and complete all Duel the Dragon expansion challenges.

Tsunami of Pain (15) - Deal 12 combat damage to an opponent in a single attack with one blue creature.
Salt in the Wound (15) - An opponent's last permanent leaves the battlefield.
Madness Suppressed (20) - Defeat Sarkhan the Mad in the single-player campaign.

Jace Beleren Gamer Picture
Complete all Challenges in single player campaign.

Chandra Nalaar Gamer Picture
Beat the single player campaign on any difficulty.